The structural characteristics of a fibre reinforced laminate are usually governed by the amount, type and orientation of the reinforcement fibres. Typically, the stiffness and strength of fibres can only be taken into account to the extent that loading occurs in the longitudinal fibre direction. Therefore, a traditionally designed laminate assumes that the fibres of the finished laminate will be oriented in the same direction as the direction of the fibres when placed in the mould. However, in some cases wrinkles in the fibre layers may occur as a result of the manufacturing process. In such cases the wrinkled fibres no longer have the desired orientation, and severe overload of the laminate may be the result.
Wrinkles in fibre reinforced laminates are typically prevented by a combination of arrangements. The laminate thickness is kept below certain limits in order to minimise exothermal heat generation. Moulds and other surfaces on which the laminate is built up are maintained at a high quality. Curing is carried out at carefully controlled temperature gradients so as to minimise differences in the thermal expansion.
If wrinkles do occur in fibre reinforced laminates despite preventive action repair or rejection of the laminate will usually be required, as the loss of stiffness and/or strength in wrinkles will often exceed any realistic safety margins.